1. Field of the Invention
The present invention relates to a reel sensor and, in particular, to a reel sensor which is mounted on a printed circuit board and includes an optical path adapted to cross the rotation loci of reel sensing projections in order to detect the number of rotations or the rotation condition of a tape winding reel employed in a video cassette recorder (VCR), a video cassette player (VCP), an audio cassette recorder, a digital cassette recorder, and the like.
2. Description of the Related Art
In FIG. 10, conventionally, a reel sensor 40, which is used to detect the number of rotations of a tape winding reel 47 provided in a VCR which is one of electric appliances and also to detect the rotation condition of the tape winding reel 47, that is, whether the reel 47 is rotating or not, is disposed under a deck chassis 41 provided within a chassis case (not shown) of a VCR main body. The chassis case has a function as a light shield plate to shield the light coming from the outside. On the deck chassis 41, besides the tape winding reel 47, there are placed VCR drive mechanism elements such as a rotary drum (not shown), a tape loading arm (not shown) and the like. The reel sensor 40 is provided on a printed circuit board (PCB) 43 disposed under the deck chassis 41, and is set at such a position that a plurality of projections 45 spaced at predetermined distances on the back surface of the reel 47 are able to cross a photointerrupter 44 by means of leads 42. The leads 42 are soldered to the printed circuit board 43. The photointerrupter 44 includes therein a light emitting diode (infrared LED) or a light emitting element which emits infrared rays, and a phototransistor or a light receiving element to which an infrared filter is applied to permit only the infrared rays to pass therethrough. When the projection 45 crosses between the infrared LED and the phototransistor with the infrared filter applied thereto, the infrared rays are shielded. By detecting the light receiving condition of the phototransistor, it is possible to detect the rotation condition of the reel 47, that is, whether the reel 47 is rotating or not, and the number of rotations of the reel 47 (see Japanese Utility Model Unexamined Publication No. Hei. 5-59622).
However, there are still left some problems to be solved in the conventional tape reel sensor 40. That is, since the reel sensor 40 requires parts respectively having the long leads 42, not only the parts are difficult to manufacture and are thus increased in costs, but also the productivity thereof is lowered when they are assembled.